TORONTO - Ontario's auditor general should investigate the cost of another energy project that the governing Liberals have abruptly scrapped, the New Democrats said Tuesday.

Voters should know exactly how much the Liberals spent moving ahead with nuclear expansion plans that weren't needed and the province couldn't afford, said NDP critic Peter Tabuns.

"As you all know, the Liberals are sometimes not forthcoming with the actual costs of their energy projects," he said.

"We need to know the full costs. We need to know what the burden would have been on the people of Ontario."

If the Liberals change their plan again, Tabuns said ratepayers would be on the hook, just as they are for the estimated $1.1-billion cost of the Liberal decision to cancel two gas plants ahead of the 2011 election. That was far more than the $230 million the Liberals originally claimed.

Two days after auditor general Bonnie Lysyk released her report on the costs of cancelling the Oakville plant, the Liberals announced they were abandoning plans to build two new nuclear reactors. But they left the door open to building new reactors should projected energy demand rise in the future.

They're still planning to go ahead with the refurbishment of existing nuclear reactors at Bruce Power near Kincardine and the Darlington Nuclear Generating Station in Clarington.

Energy Minister Bob Chiarelli said last week that costs have fallen since the government first paused its plans to build new reactors in 2009, when the estimated price was said to be as high as $26 billion. But it wasn't enough to justify building new nuclear when the province has an energy surplus, he said.

Tabuns said it's been known for years that new nuclear power wasn't needed, but the Liberals pushed ahead anyway.

Beckie Codd-Downey, a spokeswoman for Chiarelli, acknowledged that $180 million has already been spent on environmental approvals, project planning, public and stakeholder consultations.

Tabuns said he's also concerned about the true cost of refurbishing the existing reactors.

"They don't have a business case for proceeding there," Tabuns said.

"They haven't done comparison with the alternatives. For instance, importing power from Quebec, which is much cheaper than any refurb power is going to be."

The Liberals may also sign contracts before they know the final cost, he added.

"That's a huge concern for anyone who pays a hydro bill in this province."

Premier Kathleen Wynne said she's not backing down on refurbishing the aging fleet, since Ontario currently gets about 50 per cent of its electricity from nuclear generation.

The government is already looking at conservation and has been working on improving transmission, she said. But the province still needs nuclear power.

"Those are not new ideas," Wynne said. "Those are things that we have already established are going to be part of our long-term energy plan."

All of the expenditures related to new nuclear planning are reviewed by the independent Ontario Energy Board as part of the rate-setting process, said Codd-Downey.

"The NDP confirmed yet again they have no plan to meet Ontario's energy needs," she said in an emailed statement.

"They oppose emission-free and reliable nuclear power — which makes up the backbone of our energy mix — with no plans to replace it or the tens of thousands of jobs in the sector."

The Progressive Conservatives, who support more nuclear energy, said the wasted cash on a plan that the Liberals ended up scrapping just adds to the public dollars they've flushed down the drain.

"This is just an ongoing saga," said Tory Rob Leone. "We don't have this money to be spending."